Method for Making Filter Element

ABSTRACT

A filter includes a filter element formed of filter media, and a plastic framework molded and bonded to and structurally supporting the filter media. One embodiment desirably provides a two-component assembly consisting solely of two components, namely the filter media and the plastic framework molded thereon. In a further embodiment, the plastic framework includes a resilient seal integrally molded therewith and of the same plastic material thereof, eliminating a separate component for the seal. In a further embodiment, a filter combination includes a primary filter element and a secondary filter element. In a further embodiment, a resilient integrally molded seal is provided.

BACKGROUND AND SUMMARY

The invention relates to filters, and more particularly to a highefficiency, low restriction, cost effective filter.

There is continuing demand for fluid filters exhibiting high efficiencyand low restriction at reduced cost. The present invention addresses andsolves this need in a simple and effective manner.

In one desirable option, an incinerable and/or recyclable filter isprovided, enabling green label product designation, which is significantin various markets.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a perspective view of a filter element constructed inaccordance with the invention.

FIG. 2 is an enlarged view of a portion of FIG. 1.

FIG. 3 is a side view partially in section of a filter combination inaccordance with the invention.

FIG. 4 is a schematic end view of an alternate embodiment of a filterelement in accordance with the invention.

FIG. 5 is like FIG. 4 and shows another embodiment.

DETAILED DESCRIPTION

FIG. 1 shows a filter 10 having an annular filter element 12 with ahollow interior 13 and extending axially along an axis 14 betweendistally opposite first and second axial ends 16 and 18. The filterelement includes filter media 20, preferably high efficiency, lowrestriction non-pleated non-woven synthetic filter media, to bedescribed, and a plastic framework 21 molded and bonded to andstructurally supporting filter media 20. Filter media 20 has an exterior20 a facing exteriorly away from hollow interior 13, and has an interior20 b facing inwardly toward hollow interior 13, as shown at the cut-awayportions of FIGS. 1, 2. Framework 21 is preferably provided by anexternal plastic frame 22 a which includes a rib network 24 a having aplurality of interconnected ribs extending along the exterior 20 a offilter media 20 and bonded thereto, to be described. Rib network 24 aincludes arcuate ribs such as 26 a extending laterally relative to axis14 and providing the filter media with torsional loading resistance,each of the arcuate ribs being bonded to the filter media. Rib network24 a includes a plurality of axially extending axial ribs such as 28 aproviding the filter media with columnar compressive loading resistance,each of the axial ribs being bonded to the filter media. Ribs 28 aextend along axis 14 and are preferably tapered relative thereto toprovide a frusto-conical filter element. Framework 21 is also preferablyprovided by an internal plastic frame 22 b which includes a rib network24 b having a plurality of ribs extending along the interior 20 b offilter media 20 and bonded thereto. Rib network 24 b includes aplurality of axially extending axial ribs such as 28 b providing thefilter media with columnar compressive loading resistance, each of theaxial ribs being bonded to the filter media. Ribs 28 b extend parallelto ribs 28 a. Inner rib network 24 b includes only axial ribs 28 b, butmay include partial arcuate ribs such as 26 b which do not extend fullyarcuately between adjacent axial ribs 28 b but instead have a partialarcuate extension formed during mold flow. The outer and inner ribnetworks 24 a, 24 b have open areas such as 30 substantially larger thanthe area of the ribs, for reduced restriction, and reducing structuralblockage.

Frame 22 a of framework 21 is along the exterior 20 a of filter media20. Frame 22 b of framework 21 is along the interior 20 b of filtermedia 20. Filter media 20 is preferably sandwiched between the notedexterior and interior sets of ribs on opposite exterior and interiorsides 20 a, 20 b thereof and bonded respectively thereto. In oneembodiment, the filter is an outside-in filter wherein fluid to befiltered flows laterally inwardly through the filter media as shown atarrows 32 into the hollow interior of the filter, and then the cleanfiltered air flows axially rightwardly in FIG. 1 as shown at arrow 34.The noted bonding and rib structure prevents collapse of filter media20, which is desirable in high pressure and/or high vacuum situations,and in other applications and conditions where desired, for examplesevere conditions in an internal combustion engine intake air filteringapplication involving wet dirty fully loaded combustion intake air. Theouter frame protects the filter media from damage during installation.The inner frame prevents media collapse under flow conditions. Both theouter and inner frames provide torsional and compressive strength forinstallation. The filter may also be used in inside-out applicationswhere the direction of fluid flow is opposite to that noted above, inwhich embodiment the outer frame prevents media collapse under flowconditions. By bonding the media to the framework, the torsionalstrength is increased, which helps maintain element integrity duringinstallation.

Ribs 26 a, 26 b, 28 a, 28 b are bonded to filter media 20 by at leastone of, and preferably both of, a) a chemical bond and b) a mechanicalbond. Filter media 20 is composed of material selected from the groupconsisting of synthetic, glass, cellulose, ceramic, carbon, and metallicmaterial. In a preferred embodiment, in combination each of framework 21and filter media 20 is composed of material selected from the groupconsisting of organic, synthetic, and polymeric material selected suchthat filter element 12 is incinerable. In a further embodiment, each offramework 21 and filter media 20 is composed of thermoplastic material,and further preferably in combination the material of framework 21 andthe material of filter media 20 are of the same thermoplastic recyclingclass such that filter element 12 is recyclable. Further in thepreferred embodiment, filter media 20 is composed of fibers, and thematerial of framework 21 is selected from a family chemically compatiblewith the material of the fibers to chemically bond ribs 26 a, 26 b, 28a, 28 b of framework 21 to filter media 20, and also such that theplastic material of the ribs entangles some of the media fibers toadditionally mechanically bond the ribs of the framework to the filtermedia, such that the ribs of the framework are both chemically andmechanically bonded to filter media 20. In one embodiment, filter media20 is provided by polyester fibers, and the material of framework 21 isselected from the group consisting of polyester, polypropylene, andresin. In one embodiment, the material of framework 21 is polyesterselected from the same polymeric family as the noted polyester fibers offilter media 20 to chemically bond ribs 26 a, 26 b, 28 a, 28 b offramework 21 to filter media 20, and also such that the polyesterplastic of ribs 26 a, 26 b, 28 a, 28 b of the framework entangles someof the polyester media fibers to additionally mechanically bond ribs 26a, 26 b, 28 a, 28 b of the framework to the filter media 20, such thatribs 26 a, 26 b, 28 a, 28 b are both chemically and mechanically bondedto filter media 20. In one embodiment, the material of framework 21 ispolyester with glass reinforcement. In another embodiment, the materialof framework 21 is polypropylene, and the polypropylene plastic of ribs26 a, 26 b, 28 a, 28 b of the framework entangles some of the polyestermedia fibers to mechanically bond plastic framework 21 to filter media20. In one embodiment, the framework material is polypropylene withglass reinforcement. In another embodiment, the framework material ispolypropylene with talc reinforcement. In a further embodiment, thematerial of framework 21 is a plastic resin.

In further preferred embodiments, the material of filter media 20 is PET(polyethyleneterephthalate) non-woven polyester. The material offramework 21 is preferably chosen from two different plastic families.In the first family, the material of framework 21 is that known underthe tradename RYNITE 415HP-BLACK, DuPont Rynite PET Polyester. This typeof formulation, involving 15% glass reinforcement with a toughener addedin the formulation, was selected because it provides the same polymericfamily to be melt bonded during injection molding of the framework toprovide a PET plastic to PET media bond, resulting in a more robuststructural construction including between media fibers and an integrallymolded rib network 24 a, 24 b and because such polymeric bond alsoprovides some plastic working its way through the fibers of the filtermedia and providing a mechanical bond as well. This selection was alsomade because the enhanced robustness provides additional vacuumresistance under severe conditions, including a wet dirty fully loadedprimary filter failure when the present filter is used as a secondaryfilter in combination, to be described. This selection was also madebecause the enhanced robustness provides additional torsional loadingresistance including under severe conditions including loading andunloading during service. This selection was also made because theenhanced robustness provides additional columnar collapse bucklingresistance under severe service conditions, including installation withhighly compressive loads. This selection was also made because itprovides more heat resistance than polypropylene. In the second family,20% glass-filled or 30% talc-filled polypropylene is selected, with aformulation involving 20% glass reinforcement with a toughener added inthe formulation. This selection provides more economical pricing. Thisselection also provides a dissimilar polymeric family to be mechanicallymelt bonded via polymer chain entanglement amongst the filter mediafibers during the injection molding sequence during molding of framework21 to provide a polypropylene plastic to PET filter media mechanicalbond. This results in a robust structural construction between PETfilter media fibers and the integrally molded rib network 24. Theremaining reasons for this selection are similar to those aboveindicated for the first noted family, except that this second family ispreferably not used in hot environments above about 180° F. because theplastic of the framework may deflect more easily under loads. Otherresins may be used, such as nylon, ABS(acrylonitrile/butadiene/styrene), PPS (polyphenylene sulfide), and thelike.

Framework 21 extends axially along axis 14 between distally oppositefirst and second axial ends 36 and 38 at the noted respective first andsecond axial ends of the filter element. Framework 21 at the noted ribsis molded to and bonded to filter media 20 along the axial extensionthereof. The noted first end 36 of the framework has an outer peripheralsurface 40 having one or more resilient seals 42, FIGS. 1, 2, overmoldedtherewith. Seals 42 and ribs 26 a, 26 b, 28 a, 28 b are the same plasticmaterial of the framework 21 and are integrally molded with theframework on filter media 20. Seal 42 is provided by at least one, andin the disclosed embodiment of FIGS. 1, 2, three flexible annularflanges extending obliquely to axis 14 and radially deflectable relativethereto to seal against a circumscribing portion of a filter housingtherearound, one embodiment of which is described hereinafter. Ribnetworks 24 a, 24 b include the noted plurality of axial ribs 28 a, 28 bextending axially between first and second axial ends 36 and 38 of theframework. A plurality of trusses 44, FIG. 2, at first axial end 36 ofthe framework extend radially between respective axial ribs 28 a andannular flange 42 for supporting the latter. The noted arcuate ribs 26 aextend obliquely to axis 14 and laterally relative to the axialextension of framework 21. Arcuate ribs 26 a obliquely point in the sameoblique direction as annular flanges 42 providing the noted seal. Theseal provided by one or more flanges 42, the axial ribs 28 a, 28 b, andthe arcuate ribs 26 a, 26 b are all integrally molded on filter media 20as a single unitary integrally molded framework.

The integral flex seal rings provided by flanges 42 provide not only aflexible seal but also a spring-type retention by forcing the flex ringsprovided by flanges 42 into a drafted surface, preferably conical. Thiseliminates the need for providing a seal from urethane potting as in theprior art. The thickness of the rings is selected to provide enoughretention under vibration to hold the filter in place and prevent axialbacking-out thereof. The retention force is selected so as not to havetoo much interference, otherwise making installation and extractiondifficult, but still provide enough retention to resist vibrationinduced axial back-out. In a further embodiment, if vibration back-outis of concern, an interference fit retention mechanism may be provided,for example as shown in U.S. Pat. No. 6,383,244, incorporated herein byreference, and further described hereinafter. In such embodiment,intermittent detent undercuts may be provide to hold back the end-mostflex ring flange 42 (rightmost in FIG. 1).

It is significant that filter element 12 is a two-piece assemblyconsisting, in the preferred embodiment, solely of two components,namely filter media 20 and plastic framework 21 molded thereon. Theplastic framework includes a resilient seal 42 integrally moldedtherewith and of the same plastic material thereof, eliminating aseparate component for the seal, such that the filter element remains atwo-component assembly, including the seal. The framework extendsaxially along axis 14 between distally opposite first and second axialends at the noted first and second axial ends of the filter element.Framework 21, including first and second frames 22 a and 22 b, is anintegrally molded singular component, including integral connectionbetween frames 22 a and 22 b at at least one of and preferably both ofthe noted first and second axial ends 38 and 40. The filter elementremains a two-component assembly consisting solely of two components,namely filter media 20 and framework 21 molded thereon.

FIG. 3 illustrates a desirable filter combination and construction,including implementation of the filter element 12 of FIGS. 1, 2 incombination with a primary filter element 52, and uses like referencenumerals from above where appropriate to facilitate understanding.Filter 50 includes a housing 54 extending along axis 14 between firstand second axial ends 56 and 58 at respective first and second housingsections 60 and 62 mounted to each other at interface 64, as is known,for example as shown in U.S. Pat. Nos. 6,149,700, 6,402,798,incorporated herein by reference. As is known, fluid to be filtered,e.g. air, enters housing inlet 66 as shown at arrow 68 and flows intoouter annular chamber 70 in a spiral path and then flows laterallyinwardly as shown at arrow 72 through primary filter element 52 andsecondary filter element 12 into hollow interior 13 of the latter andthen flows axially rightwardly as shown at arrow 34 to housing outlet74, which may include a 90° elbow at 76, or may be a straight outlet.Annular primary filter element 52 includes pleated filter media 78extending axially in the housing between first and second axial ends 80and 82 and having a hollow interior 84, for example as shown in U.S.Pat. Nos. 6,149,700, 6,216,334, 6,306,193, 6,391,076, 6,416,561,6,641,637, incorporated herein by reference. Annular secondary filterelement 12 preferably includes non-pleated non-woven filter media 20extending axially in hollow interior 84 between first and second axialends 16, 18, as above described. Secondary filter element 12 furtherincludes the noted plastic molded framework 21 molded and bonded to andstructurally supporting non-pleated non-woven filter media 20 in hollowinterior 84. As in the noted incorporated '700 patent, pleated filtermedia 78 of primary filter element 52 has a plurality of pleats in anannulus having an outer perimeter 86 defined by a plurality of outerpleat tips, and an inner perimeter 88 defined by a plurality of innerpleat tips, wherein fluid to be filtered flows through primary filterelement 52 from an upstream dirty side at outer annular chamber 70 to adownstream clean side at hollow interior 84, and flows axially in thehollow interior. Also as in the incorporated '700 patent, primary filterelement 52 has an axial flow passage 90 extending along axis 14 andincluding the flow as shown at arrows 34 and 92, and circumscribinghollow interior 84 and having a flow perimeter 94 greater than innerperimeter 88. Flow passage 90 corresponds to flow passage 56 in theincorporated '700 patent. Flow arrows 34 and 92 correspond respectivelyto flow arrows 58 and 59 in the '700 patent. Outer and inner perimeters86 and 88 correspond to respective outer and inner perimeters 30 and 34in the '700 patent. Flow perimeter 94 corresponds to flow perimeter 60in the '700 patent. Primary filter element 52 has first and second endcaps 96 and 98 of soft resilient compressible material, such as foamedpotted urethane. End cap 96 has an inner perimeter at 94 greater thaninner perimeter 88. End cap 96 corresponds to end cap 66 of theincorporated '700 patent and partially covers the rightward axial endsof the pleats of pleated filter media 78 such that the laterally outwardportions 100 of the axial ends of the pleats are covered by end cap 96but not the laterally inward portions 102 of the axial ends of thepleats, such that the laterally inward portions 102 (corresponding tolaterally inward portions 74 in the incorporated '700 patent) areuncovered and exposed at the rightward axial end of filter element 52,to in turn allow axial flow therethrough as shown at arrow 92,corresponding to axial flow at 59 in the incorporated '700 patent. Thisadditional or increased axial flow is also shown in the notedincorporated U.S. Pat. Nos. 6,261,334, 6,306,193, 6,391,076, 6,416,561,6,641,637.

Secondary filter element 12 in FIG. 3 is downstream of primary filterelement 52 and filters both the flow in the hollow interior and theadditional flow 92 between flow perimeter 94 and inner perimeter 88. Theadditional flow 92 turns laterally inwardly as shown at arrow 104 andflows through secondary filter element 12 and joins axial flow 34. Firstaxial end 16 of non-pleated non-woven filter media 20 of the secondaryfilter element extends axially beyond first axial end 80 of pleatedfilter media 78 of the primary filter element 52 and is axially spacedtherefrom by an axial gap 106 therebetween. Non-pleated non-woven filtermedia 20 has a first section 108 radially aligned with pleated filtermedia 78 of primary filter element 52, and has a second section 110radially aligned with axial gap 106. The junction 112 of first andsecond sections 108 and 110 is radially aligned with axial end 108 ofpleated filter media 78. Fluid flow through the filter has a first pathas shown at 72 flowing laterally from pleated filter media 78 thenlaterally through first section 108 of non-pleated non-woven filtermedia 20, and has a second additional path flowing axially at 92 fromaxial end 80 of pleated filter media 78 through the area 102 betweenflow perimeter 94 and inner perimeter 88 then turning in axial gap 106as shown at arrow 104 and flowing laterally through second section 110of non-pleated non-woven filter media 20. Axial gap 106 is axiallybetween end cap 36 of secondary filter element 12 and axial end 80 ofpleated filter media 78. End cap 96 of primary filter element 52circumscribes both axial gap 106 and end cap 36 of secondary filterelement 12. Filter housing 54 at outlet end 56 has an annular flange 114extending axially between end cap 96 of primary filter element 52 andend cap 36 of secondary filter element 12 and engaging and sealing eachof end caps 96 and 36. A detent retention arrangement may also beprovided for further retaining the secondary element, for example asshown at detent 60 and flange 46 in U.S. Pat. No. 6,383,244,incorporated herein by reference. Filter housing 54 further includes avalved discharge purge outlet 116 for purging collected particulatecontaminant, as is known. It is preferred that filter element 12 taperfrom a first lateral cross-sectional area at first axial end 16 to asecond lateral cross-sectional area at second axial end 18, FIG. 1, andthat the noted second lateral cross-sectional area be less than thenoted first lateral cross-sectional area. The resulting frusto-conicalshape provides a large open area at the rightward outlet end 16 in FIG.3 and makes the filter element 12 well suited for use as a secondaryfilter element for the noted primary filter element 52 of the abovenoted incorporated patents providing the noted additional flow. Thearrangement in combination provides reduced restriction within a smallpackage satisfying increasingly demanding space constraints andaffording high efficiency, all while being environmentally friendly. Theintegral seal construction at integrally molded flanges 42 engaginghousing flange 114 is particularly cost effective.

Further embodiments include pleated and non-pleated filter media usedwith a plastic framework having only an outer frame or only an innerframe or both an outer frame and an inner frame. FIG. 4 shows a filterelement 12 a having pleated filter media 20 c bonded to inner plasticframe 22 b including axial ribs 28 b. FIG. 5 shows filter element 12 bhaving pleated filter media 20 c bonded to a plastic framework includingplastic frame 22 b having axial ribs 28 b, and plastic frame 22 a havingaxial ribs 28 a and arcuate ribs 26 a. Filter media 20 c has an upstreamdirty side, e.g. 20 d for an outside-in flow filter, comparable to 20 a,and a downstream clean side 20 e, comparable to 20 b. The framework isprovided by first plastic frame 22 a along upstream dirty side 20 d ofthe filter media, and a second plastic frame 22 b along downstream cleanside 20 e of the filter media. Frame 22 a includes the noted rib networkhaving a set of ribs 28 a extending along upstream dirty side 20 d ofthe filter media at the pleat tips or creases or bend lines 20 f andbonded thereto. Frame 22 b is provided by the noted rib networkincluding ribs 28 b extending along downstream clean side 20 e of thefilter media and bonded thereto along the interior of the noted pleattips 20 f. Filter media 20 c is sandwiched between the sets of ribs 28 aand 28 b on opposite upstream and downstream sides 20 d and 20 e of thefilter media and bonded respectively thereto.

In further preferred embodiments, the filter media is oiled and die cutand then sonically welded into a conical pre-form before it isovermolded with the plastic framework. The seam from the sonic weld isaligned along one of the noted axial ribs, so that the seam is sealed byand bonded to the plastic, minimizing a possible leak path. Stand-offssuch as 19 are provided at end 38 to space the end of the media slightlyfrom the end of the mold so that the molten plastic is free to flowaround the media to both the inner and outer ribs at such end. Innertrusses, comparable to trusses 44, may be provided on the interior ofthe element for stress bearing. The molten plastic is preferablyinjected at end 36, and media end 18 may include portions which arerecessed or otherwise slightly pushed away from the axial end to providea flow path for the molten plastic and to prevent damming thereat.

It is recognized that various equivalents, alternatives andmodifications are possible within the scope of the appended claims. Eachof the noted annular filter elements is preferably a circular annulus,though other annular shapes may be used, including elliptical,racetrack-shaped, and other closed-loop annuli. The shapes may or maynot be frusto-conically tapered. The teachings of the invention mayfurther be applied to flat panel filter elements, as well as othershapes. The noted ribs may alternatively be provided by applying heatedbars to partially melt and flatten sections of the filter media into aribbed structure, i.e. ironing ribs into the media. The preferredimplementation is an air filter, though other fluid filter applicationsare possible. In an air filter, the open areas between the ribs can belarger, since there are lower pressure drop requirements than a liquidfilter. For ease of service, a circular seal may be preferred betweenthe filter element and the housing, for example at seal 42 and thehousing at flange 114. In a desirable implementation, the filter elementis installed by pressing it or slightly twisting it into the receptaclehousing at 114 while applying pressure. The louvered, annular barbs at42 seal against the internal surface at 114 of the circular mountinghole in the housing, a duct, or an air handling conduit. As the filterelement slides into the receptacle, semi-rigid semi-flexible plastic orthermoplastic barbs 42 flex slightly inwardly, and preferably semi-rigidsemi-flexible plastic or thermoplastic walls of the receptacle at 114flex slightly outwardly, to secure and seal the filter element. A radialseal is formed between the one or more flexible barbs 42 and thereceptacle at flange 114, and, if desired, an axial face seal can beformed where the axial end 36 of the filter element meets the facingannular surface of the receptacle. To remove the filter element, theservice technician twists and/or applies a lateral force to free theface of the filter element from the holder at 114. In a furtherembodiment, the filter element is an annular filter element 12 extendingaxially along axis 14 between the noted distally opposite first andsecond axial ends 16 and 18, and framework 21 extends axially along axis14 between distally opposite first and second axial ends 36 and 38 atrespective first and second axial ends 16 and 18 of filter element 12,and the noted first end of the framework has inner and outer peripheralsurfaces, and the noted resilient seal is integrally molded with atleast one of such surfaces.

1-51. (canceled)
 52. A method for making a filter element comprisingproviding filter media composed of fibers, overmolding a plasticframework to said filter media to structurally support said filtermedia, said framework comprising a rib network comprising a plurality ofribs, selecting the material of said framework from a family chemicallycompatible with the material of said fibers, chemically bonding saidribs of said framework to said filter media during said overmolding ofsaid framework, entangling the plastic material of said ribs of saidframework to some of said fibers of said filter media during saidovermolding of said framework to additionally mechanically bond saidribs of said framework to said filter media, to both chemically andmechanically bond said ribs of said framework to said filter media. 53.The method according to claim 52 comprising providing said filterelement as an annular filter element extending axially along an axisbetween distally opposite first and second axial ends, overmolding saidframework to extend axially along said axis between distally oppositefirst and second axial ends at respective said first and second axialends of said filter element.
 54. The method according to claim 53comprising overmolding said framework to have an outer peripheralsurface at said first end of said framework having a resilient sealintegrally overmolded therewith.
 55. The method according to claim 54comprising overmolding said seal and said ribs of the same plasticmaterial as said framework.
 56. The method according to claim 54comprising overmolding said seal to form at least one flexible annularflange extending obliquely relative to said axis and radiallydeflectable relative to said axis.
 57. The method according to claim 56comprising overmolding said framework to have a plurality of axial ribsextending axially between said first and second axial ends of saidframework, and to have a plurality of trusses at said first axial end ofsaid framework extending radially between said axial ribs and saidannular flange providing said seal.
 58. The method according to claim 53comprising overmolding said framework to have a plurality of arcuateribs extending laterally relative to the axial extension of saidframework.
 59. The method according to claim 53 comprising overmoldingsaid framework to have a plurality of axial ribs extending axiallybetween first and second axial ends of said framework, and a pluralityof arcuate ribs extending laterally between said axial ribs.
 60. Themethod according to claim 52 comprising providing said filter element asan annular filter element extending axially along an axis betweendistally opposite first and second axial ends and having a hollowinterior, providing said filter media with an interior facing saidhollow interior, and an exterior facing away from said hollow interior,overmolding said framework to form a first plastic frame along saidexterior of said filter media, and to form a second plastic frame alongsaid interior of said filter media, overmolding said framework to formsaid first frame to provide a first rib network comprising a first setof a plurality of ribs extending along said exterior of said filtermedia and overmolded thereto, and overmolding said framework to formsaid second frame to provide a second rib network comprising a secondset of a plurality of ribs extending along said interior of said filtermedia and overmolded thereto, to sandwich said filter media between saidfirst and second sets of ribs on opposite exterior and interior sides ofsaid filter media and overmolded bonded respectively thereto.
 61. Themethod according to claim 60 comprising overmolding said framework toextend axially along said axis between distally opposite first andsecond axial ends at respective first and second axial ends of saidfilter element, and overmolding said framework to form an integralconnection between said first and second frames at at least one of saidfirst and second axial ends.